SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd18b8648378df29bd6f5c6c9d8b52d7507d16c5d0541e6c1f560c2c2c5e3f972' 
  AND token = 'dzHbUM8lRRcaVROZ3WnMlReVeNWQ9hBYCyRFtHAfXu0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}